Increasing research evidence has suggested a relationship between environmental stress and infectious diseases. However, the mechanisms and directionality of the relationship remains unclear. Similarly, the exact etiology of Acute Necrotizing Ulcerative Gingivitis (ANUG), an acutely painful infection of the gingiva, is still unknown. Psychosocial stress, depression of some leukocyte functions, specific pathogenic microbiota, and serum antibody levels have all been implicated in the causal web. In a recent study we found that psychosocial stress was increased and some leukocyte functions depressed in patients suffering from ANUG when compared to controls. The measures of psychosocial stress that were increased included both "state" characteristics (current or temporary status) and "trait" characteristics (underlying or enduring behavior). The leukocyte functions which were significantly depressed included polymorphonuclear leukocyte (PMN) chemotaxis and phagocytosis, and lymphocyte response to a non-specific mitogen (ConA). The proposed study is a logical extension of this previous work. We will primarily address two questions: 1) Is the profile of the relationship between psychosocial stress and leukocyte function(s) different between persons at high risk (history of ANUG) for this infectious disease and persons without such a history, and 2) are levels of psychosocial stress, specific leukocyte functions, specific bacterial flora, and levels of antibodies to specific bacterial antigens as well as changes in the levels of the variables predictive of recurrence of ANUG. In order to address the first question, we will obtain a group of 100 former ANUG cases and 100 age-sex-race matched best friend controls. The levels of the factors will be assessed every two months over a two year period. From these data the profiles of relationships between psychosocial stress and leukocyte function will be determined. To address question 2 we will compare these factors between the approximately 25% of ANUG cases who, based on previous estimates, should develop a recurrence during this period and those who do not. By answering these questions, we will further our understanding, not only of the relationships of these factors in the causation of this acutely painful infection of the gingival soft tissues, but also of the relationship between psychosocial stress and leukocyte function in general, which may play an important role in many other infectious diseases.